Electrothermal instrument for sealing and joining or cutting tissue

ABSTRACT

An instrument and method are provided for sealing and joining or hemostatically dividing tissue, which is particularly suitable for laparoscopic and endoscopic surgery. The instrument makes use of the controlled application of a combination of heat and pressure to seal adjacent tissues, to join adjacent tissues, or to anastomose tissues, whereby tissue is heated for an optimal time and at an optimal temperature under optimal pressure to maximize tissue seal strength while minimizing collateral tissue damage. The instrument of the present invention is lightweight and therefore portable, and is particularly useful in field conditions where a source of external power may not be readily available.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/358,790, filed Feb. 21, 2006, now U.S. Pat. No. 7,211,080, which is acontinuation of U.S. patent application Ser. No. 10/436,910, filed May13, 2003, now abandoned, which in turn is a continuation of U.S. patentapplication Ser. No. 09/374,563, filed Aug. 13, 1999, now U.S. Pat. No.6,626,901, which in turn is a continuation-in-part of U.S. patentapplication Ser. No. 09/035,691, filed Mar. 5, 1998, now abandoned,which is based upon U.S. provisional patent application Ser. No.60/038,589, filed Mar. 5, 1997, both of which are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates generally to instruments and methods forsealing and joining or cutting tissue. The instruments of the presentinvention are especially intended for use during either conventionalopen surgery or endoscopic or laparoscopic surgery.

BACKGROUND OF THE INVENTION

Hemostasis, or blood clotting, can be obtained by the activation of anaturally occurring biological pathway known as the coagulation cascade.The pathway can be activated by tissue injury. This injury can come frommechanical, chemical or thermal sources. This natural biological pathwayresults in the conversion of freely flowing blood to a blood clot.Several biological elements are involved in the coagulation cascade,including tissue proteins, mainly fibrin and thrombin. Cells such asplatelets and red and white blood cells are also involved.

During surgery, hemostasis can also be achieved by direct denaturizationof the proteins found in the blood. Denaturization of a protein meansthat its characteristic three dimensional structure is altered withoutactually breaking up the protein. This direct denaturization is a purelyphysico-chemical process in which the denatured proteins bond together,forming an amorphous mass of protein which is comparable to a naturallyoccurring clot. How does denaturing a protein cause it to stick togetherwith neighboring proteins? Proteins generally have a complexthree-dimensional structure. A protein is actually a chain of smallermolecules called peptides, which peptides may have side-chains whichcontain a molecular group which can attract a molecular group on anotherside chain. The main protein chain is looped and folded on itself in acomplex way which results in the three-dimensional structurecharacteristic of the protein. This looping and folding occurs becauseof an intra-molecular attraction between side-chains of the peptides.This attraction between side-chains is generally of the “hydrogen bond”or electrostatic type. The attraction which holds the peptides togetheralong the main chain is a covalent bond. When a protein is denatured, itloses its normal three-dimensional structure. As a result of thisunfolding of the protein molecule, the side-chains on the peptides,instead of facing “inward” to fold up the protein chain are now able tobond to side chains from proteins which are neighbors. Thisinter-molecular bonding results in the formation of a lump of denaturedprotein. This process is not dependent on the activation of thebiological cascades of the natural clotting mechanism, but it is apurely physico-chemical process. For hemostasis, the tissue proteinswhich must be denatured are chiefly those in blood such as hemoglobinand albumin but also include structural proteins such as those found inthe wall of blood vessels or in other anatomical structures.

One of the best ways to denature a protein is to heat it up to atemperature high enough to cause the intra-molecular hydrogen bonds tobreak, but which is not high enough to break the much strongerpeptide-peptide covalent bonds along the main chain. A prime example ofthis process is the heating up of the clear part of an egg until itturns white. This white color means that the original clear protein hasbeen denatured.

Heat which is delivered to tissue proteins may start out as electricalenergy, light energy, radiowave energy, or mechanical (vibrational orfrictional) energy. As far as the tissue is concerned, it does notmatter what the original source of the original energy is, as long as itgets converted in some fashion to heat.

For example, if the source of the energy is a laser, then the lightenergy is absorbed by molecules in the tissue whose absorption spectrummatches the wavelength of the laser light being used. Once the lightenergy is absorbed, heat is produced, and the physico-chemical processof protein denaturation is achieved. Any sort of light energy will havethis effect, if its wavelength is such that it can be absorbed by thetissue. This is general process is called photocoagulation. Theadvantage of using a laser is that since its output is monochromatic,one can selectively heat certain tissue elements which have the rightabsorption spectrum, while sparing other tissue elements for which thelaser light is not absorbed. This principle is used commonly inophthalmology. Another advantage of using a laser is that its coherentand collimated beam can be very tightly focused on very small targets.If one does not care about spatial precision or selectivephotocoagulation of only certain tissue elements, then it is perfectlypossible to coagulate tissue by using a very bright but otherwiseordinary light.

If the source of energy is electrical currents flowing through thetissue, the process is called “electrosurgery”. What happens here isthat the current flowing through the tissue heats up the tissue becausethe tissue has resistance to the flow of electricity (“Ohmic heating”).In the case of ultrasonic coagulation, the rapid vibration of theultrasonic element induces heating in essentially the same fashion asthe production of fire by rubbing sticks together (although the rate ofvibration is much much higher and the process is more controllable).

Since it is heat that denatures and coagulates proteins, why go to allthe trouble of starting with a laser or an electrosurgery unit? Why notjust use a very simple source of heat, such as a resistance wire or,even simpler, a hot piece of metal? In antiquity, “cautery” via a hotpiece of iron was used to staunch bleeding wounds. The problem with thisapproach is not efficacy, it is control and containment of the amountand extent of tissue which is cauterized or injured.

In fact, the development of “electrocautery” in the late 1920's byProfessor of Physics William T. Bovie was spurred by the desire (of thepioneering neurosurgeon Dr. Harvey Cushing) to have a more controllableand refined means of producing heat in tissues than possible by using alarge piece of heated metal. Electrocautery uses very high frequencyalternating electrical current, since it was found that these highfrequencies did not cause tetanic (“Galvanic”) stimulation of muscletissue which occurs when direct current or low frequency current isused. To avoid muscular stimulation, it is necessary to use alternatingcurrents with very high frequencies, about several hundred thousandcycles-per-second. This high frequency falls in the range of the AMradio band, which is the reason why many electrical instruments such asmonitors used in the OR will register interference when electrocauteryis activated. There are many potential problems stemming from the use ofsuch high frequencies, including difficulty in controlling straycurrents which can injure patients and interfere with pacemakers andcomputer equipment. Electrocautery has been refined over the past fiftyyears, but it still represents a rather round-about way of gettingtissue to heat up.

Numerous instruments are known which coagulate, seal, join, or cuttissue.

For example, there are electrosurgical instruments, both monopolar andbipolar, which use high frequency electrical current that passes throughthe tissue to be coagulated. The current passing through the tissuecauses the tissue to be heated, resulting in coagulation of tissueproteins. In the monopolar variety of these instruments, the currentleaves the electrode and after passing through the tissue, returns tothe generator by means of a “ground plate” which is attached orconnected to a distant part of the patient's body. In a bipolar versionof such an electro-surgical instrument, the electric current passesbetween two electrodes with the tissue being placed or held between thetwo electrodes as in the “Kleppinger bipolar forceps” used for occlusionof Fallopian tubes.

There are many examples of such monopolar and bipolar instrumentscommercially available today from companies including Valley Lab, Cabot,Meditron, Wolf, Storz and others worldwide. A new development in thisarea is the “Tripolar” instrument marketed by Cabot and Circon-ACMIwhich incorporates a mechanical cutting element in addition to monopolarcoagulating electrodes.

With regard to known ultrasonic instruments, a very high frequency(ultrasonic) vibrating element or rod is held in contact with thetissue. The rapid vibrations cause the proteins in the tissue to becomecoagulated. The ultrasonic instrument also employs a means for graspingthe tissue while the proteins are being coagulated.

Olympus markets a heater probe instrument which uses an electricalheating wire contained in a catheter type flexible probe meant to bepassed through a flexible endoscope. It is used to coagulate smallbleeding vessels found on the inside of the gastrointestinal tract orthe bleeding vessels found in peptic or other sorts of gastrointestinalulcerations. In this instrument, no electrical current passes throughthe tissues, as is the case for monopolar or bipolar cautery. Thisinstrument would certainly not be suitable for use in laparoscopic oropen surgery in which large amounts tissue must be not only coagulatedbut also divided.

There are a number of relevant patents:

Pignolet, U.S. Pat. No. 702,472, discloses a tissue clamping forcepswith jaws wherein one has a resistance for heating the jaw, and abattery to power the heater. The coagulated tissue caused by the heatand pressure is subsequently severed along the edges of the jaws beforethey are opened;

Downes, U.S. Pat. No. 728,883, teaches an electrothermic instrument ishaving opposing jaw members and handle means for actuating the jaws. Aresistance member is installed in the jaw member, which is closed todirect contact by a plate. This instrument coagulates tissue by heat,not electrical current, applied to the tissue;

Naylor, U.S. Pat. No. 3,613,682, discloses a disposable battery-poweredcautery instrument;

Hiltebrandt et al., U.S. Pat. No. 4,031,898, concerns a coagulator withjaw members, one of which contains a resistance coil. This instrumenthas a timer mechanism for controlling the heating element. The heatingelement is used directly as a temperature sensor;

Harris, U.S. Pat. No. 4,196,734, teaches a instrument that can effectboth electrosurgery and cautery. A thermistor temperature-sensingelement monitors a heating loop and regulates the current and therebythe temperature;

Staub, U.S. Pat. No. 4,359,052, relates to a cautery instrument withremovable, battery-powered cautery heating tip;

Huffman, U.S. Pat. No. 5,276,306, discloses a pistol-grip, hand-heldheating instrument having a trigger mechanism for the battery;

Anderson, U.S. Pat. No. 5,336,221, teaches an optical thermal clampinginstrument for welding or fusing tissue, and employing a cutting bladefor separating the fused tissue;

Stern et al., U.S. Pat. No. 5,443,463, discloses clamping jaw membersthat are bifurcated by a cutting blade, having plural electrodes andtemperature sensors, and can function as monopolar or bipolar; and

Rydell, et al., U.S. Pat. No. 5,445,638, relates to a bipolarcoagulation and cutting instrument.

While each of the above mentioned references is relevant to theinvention herein, none teaches or suggests the totality of the inventiontaught and claimed here.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide a instrument forsealing, cutting, or sealing and cutting tissue.

It is also an object of the present invention to provide a instrumentfor sealing and joining tissue.

It is another object of the present invention to provide a portableinstrument which does not require an external power source.

It is a further object of the present invention to provide a instrumentwhich can be constructed to conform to the requirements of laparoscopicand endoscopic surgery, i.e., to be long and very narrow, in the rangeof a few millimeters in diameter or even narrower.

It is still another object of the present invention to provide for amethod for carrying out surgical procedures using the instrument of thepresent invention.

It is a still further object of the invention to provide a method andapparatus for optimal heating and optimal pressure to optimize tissueseal strength and to minimize collateral damage to tissue.

These and other objects of the invention will become apparent to oneskilled in the art from the following more detailed disclosure of theinvention.

SUMMARY OF THE INVENTION

According to the invention, there are three parameters that areindependently controlled—the temperature to which tissue is heated, thepressure which is applied, and the time over which the temperature andpressure are maintained. The total heat applied to the tissue is afunction of the temperature and the time. A key feature is the combined(simultaneous, partially simultaneous, or sequential) application ofpressure and heat to the tissue being coagulated for a specified amountof time, which induces the denatured proteins to bond together, which inturn assists in attaining hemostasis with less heat energy than would berequired without the pressure. Also, the total energy applied isminimized by means of the configuration and materials of the parts ofthe instrument that hold the tissue in opposition during the applicationof the heat and pressure. Using less heat energy means less collateraldamage. In addition, results can be achieved that are at least as goodas can be achieved with known electrosurgical and ultrasonic tissuecoagulation units, but with a much smaller, lighter power source, suchas a battery. Also, a very simple and direct method of heating thetissue is used. Since the basic heating element is so simple, theimproved results can be achieved at a fraction of the cost of the moreround-about means of heating tissue.

According to one aspect of the present invention instruments and methodsfor sealing, or coagulating, and cutting tissue during surgery areprovided. The instruments incorporate means for controllably heatingtissue while simultaneously applying a definite and controllable amountof pressure to the tissue being heated. Because of the combinedapplication of heat and pressure, tissue proteins will become coagulatedand blood vessels within the tissue will be sealed shut, achievinghemostasis. Optimal sealing or coagulating tissue means producing astrong and durable seal or coagulation or anastomosis with a minimalamount of collateral tissue damage. In the instruments of the inventionoptimization is achieved by a combination of the physical configurationof the part of the instrument that holds the tissue during thecoagulation process and regulation of the time, temperature, andpressure.

As part of the temperature control, heat can be applied in pulses ratherthan in a continuous manner. Pulsed heat application allows tissue thatis adjacent to the area being coagulated time to recover from theheating process and to remain viable. Also, the application of thepressure may be variable in intensity and may also be applied in apulsed or discontinuous manner.

It is an aspect of the present invention to provide a method andinstrument for the surgical treatment of biological tissue, whereinthermal energy and pressure are applied simultaneously, substantiallysimultaneously, consecutively, or alternatively, over a time such thattissue proteins are denatured and the tissue will adhere or join toitself or to other tissues, for the purpose coagulating bleeding,sealing tissue, joining tissue and cutting tissue. The minimum amount ofheat or thermal energy needed to accomplish these goals is expended, soas to minimize thermal damage to tissue adjacent to the treated site.

The instruments of the invention may also incorporate means for cutting,or severing, the tissue after the tissue has been coagulated, “cutting”including dissecting or tissue division, tissue disruption orseparation, plane development, or definition or mobilization of tissuestructures in combination with a coagulation or hemostasis or sealing ofblood vessels or other tissue structures such as lymphatics or tissuejoining. The cutting can be achieved by means of a blade which is passedthrough the coagulated tissue while the tissue is being held in the jawsof the instrument. Cutting can also be achieved thermally by use ofamounts of heat greater than the amount required to coagulate thetissues. Alternatively, cutting can be achieved by other mechanical,ultrasonic, or electronic means, including, but not limited to, shearingaction, laser energy, and RF, or a combination of two or more of theabove. In the case of using thermal energy to achieve tissue cutting,the instruments and methods minimize the amount of energy required todivide tissues with the least amount of unwanted tissue necrosis.

The heating element may be a resistance wire through which electriccurrent is passed, or the heating element may be another material whichgenerates heat when electrical current is passed through it. Theelectrical current is applied through the wire either as a continuouscurrent or as a series of pulses of definite duration and frequency.Unlike conventional electrosurgical instruments, the electric current ofthe instruments of the invention does not pass through the tissue, whichcan cause problems due to stray electric currents. The electricalelements are electrically insulated from the tissue while being in goodthermal contact. In a simple embodiment of the instrument, the totalamount of continuous current and hence the total heat energy applied tothe tissue, is limited in duration by a simple timer circuit or even bydirect visual or other sensory inspection of the treated tissue. In amore sophisticated embodiment, the pulse train configuration andduration is under control of a simple microcontroller, such as, forexample, an embedded microprocessor. With microprocessor control, athermistor heat sensor is incorporated into the part of the instrumentthat grasps the tissue being coagulated. The microprocessor takestemperature readings from the thermistor and adjusts the pulse trainconfiguration and duration to achieve the optimum temperature tocauterize or seal the tissue while minimizing unwanted collateralthermal damage. The actual value of the optimum temperature can beverified experimentally for this particular instrument.

The temperature of the sealing treatment according to one aspect of theinvention is preferably kept in the range required to denaturate tissueproteins (approximately 45° C. to below 100° C.) while avoidingexcessive necrosis to the tissue. Keeping the temperature in the rangerequired to achieve protein denaturization without excessive tissuenecrosis means that the total heat energy expended in the treatment willbe less than if the temperature were not kept in this range. The amountof heat energy expended in the treatment is related to the degree of theheat (the temperature) and the length of time for which the heat isapplied. The combined application of pressure with the heat reduces theamount of heat or the degree of temperature that would be required tohave the denatured proteins actually stick together. This combinedapplication of pressure also increases the strength with which thedenatured proteins actually stick together, for a given amount of heatenergy at a given temperature.

The amount of pressure applied is regulated by springs or other elasticelements, or mechanically functional equivalents, which will result inthe tissue being held with a predetermined amount of force per unitarea, in spite of variations in the size or thickness of the tissuebeing sealed or coagulated. The pressure may also be regulated bymechanical elements or spacers or by the geometry of the pressureproducing elements. As with the temperature value, the exact value forthe pressure to be applied can be verified for this instrument withappropriate measurement calibration.

The controlled application of a combination of heat and pressure whichis sufficient but not excessive to produce a durable coagulation or sealhas the result that only a relatively small amount of heat energy isneeded. That only a relatively small amount of heat is needed means thatrelatively small electrical batteries can be used as the energy sourceto produce the heat. A instrument of the invention can therefore be freeof bulky and heavy external power generators such as are required withconventional electrosurgical, laser or other instruments for coagulatingtissue. Because small batteries can be used to power the instrument, theinstrument can be made quite compact and light weight, as well asportable and/or disposable. The use of batteries or other sources of lowvoltage direct current facilitates the avoidance of hazards andinconveniences caused by electrical interference and stray currents,which occur in conventional high-frequency electrosurgical instruments.Laser eye hazards are also thereby avoided.

Since the heating elements and pressure producing elements of theinstrument may be inherently simple and inexpensive to manufacture, thepart of the instrument that comes in contact with tissue can be made ina disposable manner, if desired, while the more expensive portions ofthe instrument can be made to be reusable. If the instrumentincorporates a simple timer, instead of the microprocessor-thermistorcontroller, the entire instrument including batteries can be made veryinexpensively and to be disposable.

Different embodiments of this instrument employing the same generalprinciple of controlled application of a combination of heat andpressure can be used to join or “weld” adjacent tissues to produce ajunction of tissues or an anastomosis of tubular tissues. The joining oftissues is essentially a special case of the controlled coagulation oftissue proteins to achieve hemostasis.

It is a further aspect of the present invention that such heat andpressure effects will be spatially confined by the physicalconfiguration and materials employed in the construction of theinstrument. The configurations and construction materials are such that(1) the tissue is held in apposition with enough pressure to effect astrong union of the denatured proteins but not enough pressure to causenecrosis of the tissue, and (2) the heat is concentrated on the tissuebeing treated by means of the material of the jaws which hold the tissuebeing treated, such material being a thermal insulator which preventsthe heat from being expended on heating adjacent tissues. Such materialmay also employ a reflective layer or coating to reflect back thetreated tissue heat energy that would otherwise be lost to thermalradiation. Such material may also have a geometry or be shaped in such away to focus the thermal energy on the treated tissue and away fromtissue not intended to be treated. For example, the jaws of theinstrument may have a concave or parabolic inner surface to focus thethermal energy.

It is a further aspect of the present invention that such effects willbe spatially confined by the kind, amount, and duration and temporaldistribution of the energy delivery. The energy could originate as heat,light, sound or electricity, chemical, or other forms of energy, as longas this energy is converted to heat to denature tissue proteins. In apreferred embodiment, the energy would be delivered from a simple, lowcost thermal heating element which could be powered by a batterycontained in the instrument itself. The energy could be delivered in acontinuous, or pulsed or intermittent mode, at variable or constantintensity. Pulsed or intermittent delivery of energy can produce aspatial confinement of the energy distribution. Feedback (includingoptical, thermal, spectroscopic, among others) and a microprocessorcould be used to control the thermal effect. In the case of tissuecoagulating, sealing or joining, the temperatures produced by the energysource could be the range of from about 45° C. to about 100° C. for aduration long enough to produce denaturation of the proteins in thetreated tissue.

The heat or energy delivery source may be a simple electricallyresistant wire, straight or curved, a grid or pattern of wires, or athin-film or coating of electrically resistant material. One or moreenergy elements may be used. They may target some or all of the tissuetreated by the pressure elements. The energy delivery source may beintegral with or separate from the pressure elements. Cutting elementsmay be incorporated into the energy elements. The energy or heat sourcemay move or be fixed. The energy may be delivered in a similar ordissimilar plane compared to the direction of pressure application. Theenergy or heat source may be constructed in such a way that its shapeand size may be varied to conform to different anatomical situations,tissue shapes and thicknesses. For example, an inflatable balloon coatedwith an electrically resistant material might be employed as the heatsource. Another example would be that the heat source might have anexpandable fan type configuration which could enlarge (“fan out”) tocover a larger surface or a smaller surface as needed. Another examplewould be a flexible sheet type configuration that could wrap around thetissue to be treated.

It is a further aspect of the present invention that such effects willbe spatially confined by the kind, amount, and duration or temporaldistribution of the pressure delivery acting in conjunction with theenergy or heat source. The delivery of pressure will usually be from aminimum of two elements of the apparatus rather but may in some cases befrom simple abutment or pressing of a single element against tissue, asin the example of the circular cutting wheel or a coring biopsyinstrument. Any combination of geometric arrangement between the energysource and the pressure source may be produced, including combinedenergy-pressure sources and separate energy and pressure sources. Aconstant requirement is that the energy element deliver energy to atleast some of the tissue that is subjected to pressure by the pressureelement. The pressure element likewise may be variable in its shape,being able to adjust its shape before or during the application of theenergy or pressure to accommodate for different anatomical situations,tissue shapes or thicknesses. Cutting elements or other elements forshaping or forming the tissue may be incorporated with the pressureelement. For example, the pressure element may be comprised of aflattened side with an acute up-angled center to produce a combinationof cutting effect over the center with compression along the sides. Thepressure applied may be constant or variable over time and the relationof the pressure elements to the tissue may be constant or variableduring application of the pressure and energy or both. Motion of theappropriately configured pressure elements may be used to effect cuttingbefore, during or after application of the energy or pressure. Thevariable application may likewise be controlled by feedback frompressure transducers or strain sensors acting with a microprocessor.

It is a further aspect of the invention that a completely separatecutting element could be used in addition to separate energy andpressure elements. It is also an aspect of the invention that mechanicaltissue fastening instruments including sutures, staples, clips, bands,screws, plates or tacks could be incorporated into the instrument. Inthis case the thermal energy and pressure would be used to providemainly coagulation and sealing and the mechanical elements would provideadditional strength to the tissue joint or anastomosis.

The invention can be used in either open, laparoscopic, endoscopic orany form of minimally invasive surgery. Surgical instruments based onthis invention could be long and thin, suitable for laparoscopic orminimally invasive approaches.

The parameters of temperature, time, pressure, as well as the anyadjustable physical configuration or geometry of the instrument mightvary depending on the type, size, and thickness of tissue being treated.These parameters may be experimentally determined before the actualtreatment and incorporated into the instrument by means of a “look-up”table in a microprocessor or by means of simple markings andcalibrations of adjustable knobs, dials, etc., of the instrument.

For the purpose of thermally joining or anastomosing two hollow tubularstructures, e.g., small blood vessels or vas deferens, a preferredembodiment would incorporate two circular or cylindrical elements. Suchcylindrical elements would be is designed to fit one into the other,acting as a jug or temporary stent which would hold the two tubularstructures together while heat was applied. The tubular structures wouldbe held in such a way to provide either a certain amount of overlap orend-to-end contact. As in previous embodiments, the amount of coaptivepressure which is being applied would be optimized according to thetissue type and thickness. The heat would be provided by a heatingelement or elements incorporated into the cylindrical jigs or stents andsituated to apply the heat to the parts of the two tubular structureswhich are in overlap or in end-to-end contact. As discussed above, theamounts of heat and pressure applied are the minimum required to producea secure anastomosis with the least amount of collateral damage.

Another embodiment of this instrument would employ a circular mechanicalcutting element, suitable for obtaining “core” biopsies of solid organssuch as the liver or a kidney. This circular mechanical cutting element,shaped like a cylinder with sharp edges at one end, would incorporate anelectrically resistant element on the outside of the cylinder. Thiselectrically resistant element could be in the form of a thin film ofresistance material. As the mechanical cutting of the tissue was done byrotating or pushing the cylindrical cutter into the tissue, hemostasisalong the track created by the cutter would be achieved by the heatingelement on the outside of the cutter. The cylindrical cutter would beconstructed out a material, or would incorporate a layer of a material,such that the tissue core sample being removed would be insulated fromthe thermal effects of the heating element on the outside of the core.This design would allow for retrieval of tissue samples which are notdistorted by heat changes and also allow for secure hemostasis along thetract of the biopsy. In this instrument, the lateral pressure exerted bythe cylinder wall on the tissues of the track cannot be explicitlycontrolled; however, there is pressure, and this pressure is part ofattaining hemostasis.

In a further embodiment of the invention, a circular cutting wheel wouldbe mechanically rotated to cut tissue, such as skin. This circularcutting wheel would incorporate along its rim, an electrically resistantthin film. This electrically resistant element would provide forhemostasis as the rotating mechanical wheel cuts the tissue.

In a yet further embodiment of the invention, an inflatable elasticballoon could be used to apply heat and pressure to tissue. The exteriorsurface of the balloon would be coated partly or totally with flexible,optionally stretchable, electrically resistant material that will heatup when electrical current is applied. Here, the pressure exerted on thetissue can be controlled by regulation of the inflation pressure of theballoon.

Another embodiment of the invention comprises a compact electricalcutting and coagulating instrument which allows blood vessels, othervessels in the body, or organ tissue to be divided with electricalenergy while at the same time being ligated by heat-induced coagulation.This embodiment comprises a forceps or tweezer-like gripper with twoarms which may grasp a vessel or section of organ tissue with grippingareas at the tip of the arms. One arm is fitted with a protrudingcutting wire, while the other arm is provided with an anvil surface and,optionally, a recess for receiving the cutting wire. Cutting a vessel ortissue is accomplished by heating the wire and closing the tweezer armson the vessel or tissue, allowing the hot wire to cut the vessel ortissue. Sealing the vessel or tissue is accomplished when the tweezerarms have closed upon the severed ends of the vessel, whereupon theanvil surface is heated to cause coagulation of the vessel or tissue.The wire may be made of a non-stick composition comprising carbon, andthe anvil may comprise non-stick substances such as PTFE or carbon. Thecutting wire is heated to a high temperature from an electrical powersource, preferably a DC power source, and preferably powered bybatteries housed in the body of the instrument or in a portable batterypack. The anvil may be heated by radiant and conductive heat from thecutting wire, with heating wires powered from the electrical powersource, or from the cutting wire indirectly.

Optionally a standard clamp can be modified to accept a cartridgecontaining a heating element and a power supply, or an instrument usefulfor laparoscopic procedures may be the functional equivalent of theforceps described above.

The instruments of the invention can be used in surgery and areparticularly well suited to laparoscopic and endoscopic surgery. Becausethe method described uses heat energy in the minimum amount and at thelowest temperature consistent with attaining denaturation and stickingtogether of tissue proteins, instruments which work based on this methodwill be able to function more efficiently than conventional surgicalenergy instruments. Therefore these instruments can be portable and evenbattery powered, which makes them ideally suited for portable ormilitary applications.

There is no instrument or method in the prior art which specificallyseeks to obtain surgical coagulation, sealing, joining or cutting by acombination of resistant heat energy and pressure at a time, temperatureand pressure which together are sufficient but not excessive to produceprotein denaturization, and with a physical configuration and materialsof construction which promote the sticking together of the tissues beingtreated while minimizing losses of heat energy to surrounding tissuesbeyond the treatment zone.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the following description taken in connection withthe accompanying drawings, in which:

FIG. 1 is a schematic representation of one embodiment of the presentinvention;

FIG. 1A is a cross-section along line I-I of the embodiment in FIG. 1with the jaw in closed position;

FIG. 2 is a top, partly cross-sectional view of the lower jaw of theembodiment of FIG. 1 showing the heating and cutting elements;

FIG. 3 is a plan view of another embodiment of the invention;

FIGS. 4 and 5 are cross-sectional views of the embodiment of FIG. 3;

FIGS. 6 and 6A are a plan view and a partial, enlarged view,respectively, of a further embodiment of the invention;

FIGS. 7 and 7A are a plan view and a partial cross-sectional view,respectively, of another embodiment of the invention;

FIG. 8 is a partly cross-sectional view of a further embodiment of theinvention;

FIG. 9 is a plan view of yet another embodiment of the invention;

FIG. 10 is a top, partly cross-sectional view of the embodiment of FIG.9;

FIG. 11 is a plan view of another embodiment of the invention forheating and cauterizing tissue;

FIG. 12 is a prospective view of a forceps embodying a cutting and/orcoagulating element in accordance with the invention;

FIG. 13 is a top view of the embodiment shown in FIG. 12;

FIGS. 14 and 15 are each partial views of a forceps arm from theembodiment shown in FIG. 12;

FIG. 16 is a cross-sectional view of the distal portions of the forcepsarms shown in FIG. 12;

FIG. 17 is a graphic representation of the temperature gradient oftissue heated with the embodiment of FIG. 12;

FIG. 18 is a graphic representation of the time vs. temperaturecharacteristics of the embodiment of FIG. 12;

FIGS. 19 and 20 are prospective views of a clamp embodiment of theinvention;

FIG. 21 is a perspective view of an embodiment of the inventionspecifically adopted for laparoscopic use.

FIG. 22 is a partially cross-sectional view of the distal end of theembodiment shown in FIG. 21;

FIG. 23 is a partially cross-sectional schematic detail of an embodimentof the distal end shown in FIG. 22; and

FIGS. 24 and 25 are each a schematic, partially cross-sectional view ofanother embodiment of the invention adapted for laparoscopic use.

DETAILED DESCRIPTION OF THE INVENTION

The invention can perhaps be better appreciated from the drawings. FIG.1 depicts a schematic representation of the instrument of the inventionshowing an upper jaw 10, a lower jaw 12, an elongated shaft 14 attachedto a handle 18, having a lever 20 for opening and closing the jaws.Upper jaw 10 is attached at hinge 11 to spring support member 13, andspring 15 is attached to both upper jaw 10 and spring support member 13to bias upper jaw 10. Lever 20 is operatively connected through rod 21to one or both of upper jaw 10 and lower jaw 12. The end of shaft 14closest to handle 18 is provided with (1) a pusher 16 which isoperatively connected through member 17 and connector 23 to a cuttingknife blade 19 housed in lower jaw 12 and (2) a trigger 22 to actuatepusher 16 which in turn actuates cutting blade 19. The lower end ofhandle 18 is provided with a rechargeable battery pack 24, which isoperatively connected to heating element actuator 27 and heating wireelement 26 in lower jaw 12.

In FIG. 1A, tissue segment 25 is clamped between jaws 10, 12, where itcan be cut by blade 19.

FIG. 2 depicts a top view of lower jaw 12 showing the relative locationsof heating wire element 26 and a slot 28 for cutting blade 19, withinjaw 12. Heating wire element 26 is in a groove of a depth such that thewire is substantially flush with the surface of jaw 12. Preferably thedistal portion 29 of heating wire element 26 is below, or out of, theplane of heating wire element 26 so that only two parallel areas oftissue will be sealed. Heating wire element 26, which preferably iscomprised of nichrome or another suitable electrically resistant metalor alloy, or an electrically resistant thin-film or coating willpreferably have a suitable, thermally conductive, electricallyresistant, non-stick coating. Examples would includepolytetrofluoroethylene (PTFE), e.g., TEFLON®, or other non-stickcoatings used in cookware. Moreover, one or both of the facing surfacesof upper jaw 10 and lower jaw 12 may optionally be corrugated,irregular, or grooved.

Both the upper and lower jaws are composed of a material, such asceramic, which is thermally insulating or thermally reflective. In thisway, the heat generated by the heating element is confined to the spacebetween the jaws, and is not allowed to spread or radiate to othertissues that may be in contact with the outside of the jaws. This isbeneficial in two ways: first, the heat generated by the heating elementis used efficiently to perform the desired sealing or coagulation, andsecond, surrounding tissues are protected from inadvertent thermalinjury.

As would be appreciated by one skilled in the art, the heating,pressure, and/or cutting functions could be mechanically,electromechanically, or electronically synchronized to obtain optimalresults according to the invention. Also, the instrument shown in FIGS.1, 1A, and 2 may optionally not have a cutter element. Such a instrumentwould be intended for situations where only heating and pressure wouldbe necessary to join tissue or to otherwise heat and cauterize tissue toproduce coagulation.

In the embodiment of the invention shown in FIGS. 3 and 4, a cylindricalmember 30 is concentrically positioned around a rod 32, the distalportion of which forms anvil 33. The distal surface of cylindricalmember 30 comprises a circular heating element 34 and a circular cuttingelement 35 arranged concentrically within heating element 34. Anvil 33is configured so that when rod 32 is moved proximally, the proximalcircular edge 36 of anvil 33 cooperates with heating element 34 tocoagulate or seal tissue.

Use of the embodiment of FIGS. 3 and 4 can be appreciated in FIG. 5,where, for example, two sections of intestine 38,39 are positioned to bejoined together. Initially one end of each of sections 38,39 is looselyconnected with ligatures 40,41 about rod 32. Then, rod 32 is moveddistally to cause circular edge 36 of anvil 33 to force portions ofintestines 38,39 into contact with heating element 34. Intestinesections 38,39 are joined together, and excess tissue is cut off bycutting element 35. Rod 32 is then pulled further in the proximaldirection to remove the excess tissue, cylindrical member 30, and anvil33.

In addition, the instrument shown in FIGS. 3 to 5 to produce circularanastomosis by relying on heat and pressure could additionallyincorporate mechanical fastening elements such as staples. Such ainstrument is shown in FIGS. 6 and 6A, where a circular staplinginstrument 42 comprises a main shaft 43, a handle 44, a staple housing45, and an anvil 46. Anvil 46 is fixedly attached to the distal end ofanvil shaft 47, which is movably slidable within staple housing 45, mainshaft 43, and handle 44.

The distal surface 48 of staple housing 45 has slots 49 for staples (notshown) and an electrically resistant coating or member 50. An innercircular member 51 with a cutting edge 52 is arranged circumferentiallyaround anvil shaft 47, as can be seen more clearly in FIG. 6A.Optionally, slots 49 and coating 50 could be coextensive so as tofacilitate direct heating of the staples.

Handle 44 comprises means for operating anvil 46 and heating element 49and for firing the staples. As would be appreciated by those skilled inthe art, a staple firing lever or member 53 can be operatively connectedto a cylindrical pushing member within stapling housing 45 that causesthe staples to be ejected from slots 49.

The operation of the circular stapling instrument would be similar tothat of instrument shown in FIG. 3, with the exception that stapleswould be fired into tissue to be joined. Preferably the staples would befired subsequent to sealing and concurrently with the cutting. Thestaples would act in conjunction with the thermal energy to enhance thestrength of the tissue seal, joint or bond while the thermal energywould enhance the hemostatic capability of the staples. Staples or othermechanical tissue fasteners could be used in conjunction with thermalenergy sealing in configurations other than circular, such as linear orangled.

FIG. 7 depicts an embodiment of the invention that is essentially atissue-core removal instrument. The tissue-core removal instrument 56comprises a cylindrical member 58 having a fixedly attached proximallyextending handle 60. Cylindrical member 58 comprises a sharp cuttingedge 62 and a heating element 64 arranged on the outer surface 66 ofcylindrical member 58. Optionally, sharp cutting edge 62 could bereplaced by a heating element to do the cutting.

Consistent with the description above, a tissue sample is obtained byinserting removal instrument 56 into an organ, with instrument 56 beingrotated as it moves forward. The rotation could be either clockwise orcounterclockwise, but preferably alternatingly clockwise andcounterclockwise, with sufficient pressure to cause edge 62 to cut.Heating element 64 will cauterize or seal tissue adjacent to the tissuesample to be removed, and when a tissue sample of sufficient depth ispositioned within cylinder 58, instrument 56 will be removed. As isconventionally done, removal instrument 56 would preferably containmeans for removing a tissue sample, such as an internal piston 59 havinga proximally-extending actuator 60 to force the sample to be ejectedfrom the distal end of removal instrument 56. As would be appreciated bythose skilled in the art, a tissue-core removal instrument mayoptionally have additional cutting means at its distal end to assist inseparation of a core tissue sample from the tissue mass.

In FIG. 8 the distal portion 70 of an electrothermal biopsy needlecomprises an outer cutting sheath 72 slidably circumferentially arrangedaround an inner slotted stylus 74 having a slot 76 to capture a tissuesample 78. The outer sheath 72 has a cutting edge 73 which separatestissue sample 78 from the rest of the tissue mass (not shown) andencloses sample 78 in slot 76 when outer sheath 72 is propelled distallyby an actuator (not shown).

Outer sheath 72 preferably has an electrically resistant film 75 coatingon its distal portion. Film 75 may have spaced-apart electrical contactsor connectors 77. In another embodiment of a biopsy needle where stylus74 has an inner cutting member (not shown), the stylus or the innercutting member, or both, may have an electrically resistant coating orfilm.

The aforementioned aspect of the invention could be incorporated intoknown biopsy instruments. See, for example, U.S. Pat. Nos. 4,600,014 and5,595,185, both of which are incorporated herein by reference withregard to their descriptions of biopsy instruments.

FIGS. 9 and 10 depict a circular cutting embodiment of the invention inwhich a disk 80 having a sharp outer edge 82 is attached at its centerto a rod 84 which is rotatingly secured to forks 86 of handle 88.Adjacent edge 82 is a circular heating element 90, which can be on oneor both surfaces of disk 80. Each heating element 90 is electricallyconnected to fork 86, for example, through one or more brushes 91.Optionally, sharp cutting edge 82 could be replaced by a circumferentialheating element to do the cutting.

FIG. 11 represents an embodiment of the invention where a heating andcauterizing instrument 92 comprises a catheter 94 and an inflatableballoon 96 sealingly attached to the distal end of catheter 94. Catheter94 comprises at least one lumen 98, which is in fluid communication withballoon 96 for inflation and deflation. The proximal end of catheter 94is in fluid communication with a regulated pressure source or inflationsource (not shown) for inflating and deflating balloon 96.

Balloon 96 has an electrically resistant film coating 100, at least twoseparate portions of which are connected to wires 102 that extendproximally along or within catheter 94 to a power source 104. Theelectrically resistant film coating 100 is intended to cover asubstantial portion, if not all, of the outer surface of balloon 96.

In use, instrument 92 with a deflated balloon 96 is manipulated within apatient's body, e.g., intracorporeally or even percutaneously, toposition balloon 96 adjacent to a site to be cauterized. Then, balloon96 is inflated so that the electrically resistant film coating 100contacts the area to be cauterized, whereupon film coating 100 isenergized with electrical energy from source 104. After the heat andpressure produce the desired effect, the power is turned off and theballoon is deflated to facilitate removal.

With regard to the embodiments of the invention depicted in FIGS. 3 to11, it should be appreciated that the respective heating elements areelectrically connected to an appropriate power supply. It is envisionedthat in each instance the power supply can be a battery or battery pack,which can be fixedly attached or integral with to the respectiveinstrument. Optionally, the battery or battery pack could be separatelymounted or positioned, such as on a clip or belt means for the operatorto wear. It is within the scope of the invention that other standardsources of electrical power, such as transformers, may also be used.Other sources of heat such as fuel, e.g., butane, or chemical reactions,may be used.

As mentioned above, one aspect of the invention concerns optimization of(1) thermal energy application, i.e., temperature and time, and (2)pressure, i.e., force and duration, to achieve maximum tissue sealstrength and minimal collateral tissue damage. Those skilled in the artwill appreciate that useful parameters will vary greatly.

However, in practical application to human tissue a voltage of fromabout 0.5 volt to about 14 volts, preferably from about 1 volt to about12 volts, will be applied to a heating element having a resistancesufficient to generate thermal energy to heat tissue to a temperatureadequate to cause denaturation of proteins. This temperature is in therange of about 45° C. to about 100° C. The pressure applied would besufficient to provide coaptation but less than would crush or destroythe tissue itself.

The strength of tissue coagulations, seals, anastomoses or welds can beexperimentally measured. For example, the strength of a coagulationproduced on the side of a lacerated blood vessel can be measuredexperimentally by first producing the coagulation and then applyingmeasured amounts of hydrostatic pressure to the inside of the vesseluntil the coagulation blows off and bleeding recommences. The strengthof a tissue weld can be measured by first joining two pieces of tissuetogether and then placing the joined tissues in a machine which attemptsto pull the tissue apart with increasing and measured amounts of force.Collateral thermal damage is also a measurable quantity in that theamount of collateral thermal damage can be readily assessed visually ormicroscopically. By use of this methodology, a table of optimizedparameters could be constructed for any type of tissue. These parameterswould be incorporated into the various instruments by means of selectingthe voltage, current, and resistance of the heating elements and alsothe amount of pressure used to press the tissue together during thecoagulating/sealing/joining process, as well as the time duration of theprocess. These parameters can simply be incorporated into the instrument(i.e., simple mechanical timer, fixed preset voltage and current, andspring-loaded pressure instruments, or, we can incorporate more flexibleand active controls based on microprocessor regulation of the heatingprocess, guided by a “look-up” table in ROM and by using sophisticatedmechanical force/pressure sensors and strain gauges). Also, for certainapplications, it may be sufficient to have a skilled operator, visuallyor by other sensing means, determine the duration of energy applicationand the amount of pressure required.

The instruments of the present invention may be constructed of anysuitable material, such as will be familiar to one skilled in the art,for example, out of a reinforced engineered plastic such as fiberglassreinforced polycarbonate, or machinable or injection-molded ceramics, orhigh temperature glass or epoxies, or mica. Alternatively they may beconstructed out of a suitable alloy steel such as 318 stainless steel,or the like. The heating element may be a simple resistive wire or maybe a thin film or coating composed of metallic, organo-metallic, ororganic materials which may be conducting or semi-conducting. The actualmaterials of construction will be a matter of choice depending uponwhether the instrument is to be employed repetitively or in a disposablemanner. Indeed, in the latter situation it is contemplated thatdifferent parts of the instrument may be constructed of metal alloyand/or plastic, in which situation the plastic disposable components canbe thrown out after each use and the more expensive metal alloycomponents reused. If sophisticated and expensive control circuitry isused, this part of the instrument could be made in a reusable manner.

FIG. 12 illustrates an embodiment of a forceps instrument 210 which maybe variously described as a pincer or tweezers. Forceps instrument 210comprises forceps arms 212 and 214, the proximal ends 216 and 218,respectively, of which are attached to switch housing 220. The outersurfaces of forceps arms 212 and 214 contain finger grips 222 to assistthe operator in holding and activating forceps instrument 210. Anoptional sleeve 221 covers the proximal portion of housing 220.

Forceps arms 212 and 214 may be formed of a suitable resilient materialsuch as stainless steel, for example, that has the desired combinationof stiffness and spring rate. For disposable applications forceps arms212 and 214 may be formed from a homogeneous plastic material, or amaterial that is filled with particulate material to increase stiffnessor abrasion resistance.

Alternatively, forceps arms 212 and 214 may be formed from a compositematerial tailored to provide the desired stiffness according to specificfunctional and ergonomic needs and to provide heat resistance forelectrosurgical and thermosurgical applications. The composite materialmay be any composite construction, e.g., fiber material, glass, carbonfiber, Kevlar, aramid, or metallic particles bound with an epoxy,polyester, or other resin, forming the composite matrix.

Forceps arms 212 and 214 may be manufactured in a unitary construction,via casting, lay-up, compression molding, lamination, or molding of apre-impregnated fiber cloth in a manner known to one skilled in the art.The forceps arms may also be molded or cut from pre-formed sheetcomposite material and glued or riveted together. Components may also befilament wound. Alternatively the components may be stainless steel witha flex circuit.

The composite matrix may also have molded into it conductive wires orstrips for transmission of electrical energy or transmission of datasignals. The carbon in the carbon fiber matrix may also be used toconduct electrical or data signals. The fiber in the matrix, which maybe carbon, glass, Kevlar, aramid, or other fiber, may be laminated suchthat the unidirectional fibers are oriented at an angle to one anotherto achieve the desired spring rate and stiffness characteristics.

One or both of the distal ends 224 and 226 of forceps arms 212 and 214,respectively, contain a heater wire 228, as shown in greater detail inFIGS. 15 and 16. Each of said distal tips 224 and 226 comprises anon-slip sleeve or “bootie”, such as heater sleeve 230 on distal tip 224and anvil sleeve 231 on distal tip 226, which sleeves may be comprisedof clear or opaque, deformable, resilient, non-stick material. Suitablematerials include polytrafluoro-ethylene (PTFE), available as TEFLON®,graphite, KAPTON, mica, or silicone. Each sleeve 230,231 evens outpressure against tissue and insulates the surfaces of forceps arms 212and 214 electrically and thermally. Sleeves 230,231 may also incorporatethermally reflective material as layers or coatings. Useful reflectingmaterials would include ceramics, thermally reflective metals, orthermally reflective polymers, such as MYLAR(® polymeric compositions.Sleeves 230,231 also prevent heat dissipation and focus heat from heaterwire 228 on a specific area, while spreading the heat sufficiently toobtain a good seal zone. By insulating and reflecting, i.e., managing,the heat generated by heater wire 228, sleeves 230,231 minimize powerconsumption to achieve the intended result. Also, the resiliency ofsleeves 230,231 is intended to lengthen the useful life of heater wire228, which becomes fragile when hot.

Switch housing 220 comprises a finger-operated switch 232, e.g., amulti-directional post-in-tube design, preferably a high current, lowvoltage switch. When a button 234 is pushed into the plane of forcepsarms 212 and 214, from either direction, switch 232 is activated so thatcurrent is provided to heater wire 228. When button 234 is released, thebutton returns to its starting position and the flow of current isinterrupted. Optionally, housing 220 comprises at least one anti-swivelguide 235 to form a channel to help maintain forceps arms 212 and 214parallel to one another. In addition, the forceps may be used with afoot-activated switch instead of a finger-activated switch. The sameswitch housing may be used, but without a finger switch. Instead, thecircuit may be completed by depressing a foot switch that is connectedvia an electrical cable between the battery pack and the forceps powercord.

In a preferred embodiment of the invention switch housing 220 comprisescircuitry to control or manage the current supply to heater wire 228.This circuitry, known generally as an “actuator”, is an important anduseful feature. Deterioration of heater wire 228 is prevented by contactof heater wire 228 with the heat sink of the pinched tissue and theopposing forceps arms. The presence of the actuator induces the operatorto apply a minimum amount of pressure to the closed forceps distal tips,which insures good sealing/welding of the vessel or organ tissues. Inaddition there is the important safety aspect that the actuator preventsinadvertent exposure of heating wires to drapes or other flammablematerials in the operating room, should the finger-operated switch beinadvertently activated.

As can be seen more clearly seen in FIG. 15, at least one distal tip ofone of the forceps arms, such as distal tip 224 of forceps arm 212,comprises heater wire 228 on the outer surface of heater sleeve 230,preferably with a slight gap between distal tip 224 and heater sleeve230, which gap could be filled with a fluid such as a gas or liquid.This provides for additional thermal insulation between heater wire 228and forceps distal tip 224. Heater wire 228 may comprise any usefulelectrically resistant, preferably non-stick material such as nichromeor an alloy thereof, graphite, nitinol, stainless steel, platinum, ortungsten, uncoated or coated with a non-stick material such as graphite.In fact, any material may be used such that the heater wire 228 has alower ohmic resistance than body tissue. This lower resistance allowsthe resistive element to be exposed but not transfer electricity throughthe tissue. The length, diameter and material selection are adjusted tooptimize sealing and cutting. Although heater wire 228 preferably has around smooth surface, wire 228 may be other then round and have atextured surface to increase traction. A flat surface would be betterfor sealing applications, whereas a pointed surface would be better forcutting applications. It is within the scope of the invention thatheater wire 228 may be a flex circuit or just a very flat wire. Whileheater wire 228 is shown in FIG. 12 as being substantially straight,heater wire 228 could instead be curved or arcuate.

Heater wire 228 is connected by solder to broader, flat wire 236, whichis in turn soldered to the distal portion 238 of a copper striplaminated to the inside surface 240 of forceps arm 212. Flat wire 236 iscovered by a polymeric sleeve 242.

Distal tip 226 of forceps arm 214 comprises sleeve 230 having a thickerinner surface 244, which inner surface 244 may comprise an integral partof sleeve 230 or a separate component that has been adhered to the innersurface of sleeve 230. In a preferred embodiment of the invention, saidinner surface comprises a separate polymeric member that has been gluedor fused with sleeve 230, optionally with molded ridges on the surfacefacing heating wire 228 to improve grip/tissue traction.

Heater wire 228 is electrically connected through cord 249 to a powersource such as a battery pack 250. Battery pack 250 can comprise anynumber of commonly available batteries (such as D cells or AA cells),dependent upon application. Battery pack 250 may optionally comprisesensing circuitry and a vibrating or auditory alarm to indicate a “lowbattery” situation, to minimize sticking and peeling of tissue when thebattery is low and heater wire 228 would not be hot enough to seal orcut. Preferably, there will be a tone from housing 230 or battery pack250 to indicate the forceps has been activated, with another tone orvibration to indicate that the battery is low. While there could be acutoff rather than a low battery signal, it is believed that a lowbattery signal is preferable. It is intended that the battery pack willbe capable of being clipped to the operator's uniform or suspended on anIV pole, or otherwise positioned in a convenient location adjacent thetreatment area. Preferably the battery pack is connected to instrument210 with a releasable connection 252 so that battery pack 250 can bereadily replaced. The proximal portion of sleeve 221 may comprise aswivel connection 253 with cord 249.

The preferred power source is a steady DC battery pack. It is within thescope of the invention that the power source could be a wall outletplug-in transformer of steady DC, pulsed DC, low frequency AC, or evenRF. One could also provide for a cutoff ability, for example, in theevent of a short circuit or wire break, and/or a temperature feedback,optionally with a control to minimize temperature for sealing andmaximizing temperature for cutting. Also, optionally there would be afeedback to power capability to automatically adjust for use underliquid conditions, e.g., saline, versus non-liquid conditions, to reducethe risk of wire burnout.

In the event that the power supply has DC/RF capability, the forceps canalso function as an RF instrument. If the distal tips of the forcepsarms were closed and then tissue was contacted, the RF/forceps would actlike a hemostatic electrode or blade. Optionally a sleeve could beremoved and replaced with a Bovie blade. (Also, the instrument could beactivated with a dedicated hand switch or a foot switch.)

A primary application of the forceps instrument shown in FIGS. 12 to 16is to seal and cut tissue such as blood vessels, other corporeal vesselsor ducts, corporeal organs, and vascularized tissue. It is also usefulfor sealing in the lymphatic system. The way in which said forceps workscan perhaps be appreciated by referring to FIG. 17, which comprises arepresentative graph of the temperature gradient in a vessel or tissue(“tissue”) to which this instrument is applied. At the portion of tissuein direct contact with or immediately adjacent to a heater wire, thetemperature of the tissue will be very hot—sufficiently hot to sever thetissue. At the same time, at the areas of tissue immediately adjacent toand roughly parallel to the “cut zone”, the tissue will be heated butnot to the same extent as in the cut zone. In these two secondary areas,each referred to as a “seal zone”, tissue will be cauterized and sealed.This tip configuration allows for expedient division and sealing ofblood vessels or vascularized tissue with the simple process of closingthe forceps arms and momentarily applying heat energy at the forcepstips. This process will divide and seal the tissue. Additionally, whenthe tissue is gripped under moderate traction, the tissue will oftenautomatically fall away from the jaws of the forceps as the heatingelement divides and seals the tissue. Heat from the heating elementconducts laterally into the adjacent tissue while it is being compressedwithin the forceps tips. As a result, this tissue is often completelysealed by the time it is divided and falls away from the forceps jaws.This way, the divided tissue will not bleed as it is divided. Thesurgeon moves to a new area of tissue to be divided hemo-statically, andthis simple process is repeated. With this approach to cutting andcoagulation, significant time and materials can be saved, reducing theneed for applying clips or ligatures, or for the use of other hemostasisproducts or techniques. Thus, with this particular embodiment of theinvention, tissue can be cut and cauterized with one fairly simplerepetitive motion.

The time vs. temperature graph shown in FIG. 18 illustrates theprinciples involved behind the process of sealing and cutting with theforceps device. After tissue is grasped between the forceps tip, theheat is activated by the button 234 at t=0. As the heating element heatsup, heat is conducted into the tissue being grasped. As the temperatureincreases with time, the tissue passes the temperature value necessaryfor sealing and hemostatis (and eventually approaches the temperaturenecessary for dividing the tissue). Tissue closer to the heater ishotter than tissue farther away from the heater. Eventually (typicallyat t=2 to 5 seconds) the tissue immediately adjacent to the heaterbecomes hot enough that it divides. This division usually occurs afterthe tissue slightly farther away from the heater has reached asufficiently elevated temperature for sealing and/or coagulation tooccur there. Alternatively a pre-programmed “lock out” interrupts thepower supply, so that the tissue remains at the appropriate temperaturefor the appropriate time, for example, 100° C. for approximately onesecond, whereupon the tissue is severed and then cools.

In the embodiment of the invention set forth in FIGS. 19 and 20, a clamp302 comprises a cartridge 304 that can be removably attached to clamp302. Clamp 302 is essentially a common surgical clamp that has beenadapted to receive cartridge 304. Cartridge 304 comprises an elongatedmember 306 having a switch housing 308 with a switch activator 310. Thedistal end of member 306 comprises a heating element 312 that is inelectrical connection with switch housing 308 and a power supply (notshown).

The embodiment of the invention shown in FIG. 21 is a modification ofthe embodiment shown in FIGS. 12 to 16 intended for laparoscopicapplication. According to this embodiment an elongated member 320 isattached at its proximal end 322 to a handle 324 housing comprising handgrips 326 and 328 attached to grip members 330 and 332, respectively.The distal end 334 of elongated member 320 comprises gripping arms 336and 338, at least one of which has a heating element 340. Gripping arms336 and 338 may optionally have sleeves (not shown).

An actuator rod 342 has a proximal end 344 rotatively attached to gripmember 330 at fastening point 346, and the distal end 348 of actuatorrod 342 is operatively connected to gripping arms 336 and 338. Grips 326and 328 and their respective grip members 330 and 332 are movablyconnected at pivot point 350, so that when grip 326 and 328 are squeezedtogether, proximal end 344 moves proximally and gripping arms 336 and338 move together. A rotating positioner 352 can rotate to in turnrotate elongated member 320 and gripping arms 336 and 338.

Grip member 332 preferably contains a finger-activated switch 352 tocontrol the flow of electricity to heater wire 340.

In FIG. 22 one embodiment of the operative connection between actuatorrod 342 and gripping arms 336 and 338 is shown. Distal end 348 ofactuator rod 342 is movably connected to a link 360 which is movablyconnected to member 362. Gripping arms 336 and 338 rotate in oppositedirections about pivot point 364 to close or open upon tissue. Whenactuator rod 342 moves in the proximal direction, gripping arms 336 and338 close together. Upper gripping arm 338 comprises heater wire 340,such as a nichrome wire, which is thermally and electrically insulatedfrom gripping arm 338 by insulator 366. Here, the distal portion 370 ofheater wire 340 is spot welded to the exterior surface 372 of grippingarm 338. The interior surface 374 of gripping arm 336 is preferablyinsulated, for example, with a silicone polymeric insulator. Heater wire340 is operatively connected through wire 376 to a power source (notshown) and/or switch 352.

A detail of FIG. 22 is shown in FIG. 23, where the relationship betweengripping arms 336 and 338 can be better appreciated, especially for hecurved embodiment shown. Member 362 and lower gripping arm 336 areintegral and cooperatively arranged with upper gripping arm 338 andmember 380 around pivot 364. The interior surfaces 382 and 374 ofgripping arms 338 and 336, respectively each having polymeric insulationinserts.

As has been shown, the materials and the principles described for thetip design of the forceps can be modified slightly and applied to theclamp and to the laparoscopic grasper. Just as the design can beadjusted to a clamp and to a laparoscopic grasper, it can be applied tovirtually any hand-held surgical instrument.

A monopolar RF version of a hook dissector is used in laparoscopicsurgery. The embodiments of the invention shown in FIGS. 24 and 25comprise a surgical dissecting instrument in the form of a hook, andthis hook offers safety advantages over the RF version since the heatingeffect is confined to the tissue caught up in the hook. The heatingelement, preferably a nichrome wire, is situated on the inner surface ofthe hook so that tissue is compressed against the heater wire whentissue is “hooked” with the instrument.

The instrument shown in FIG. 24 comprises an elongated member 402 havinga proximal end 404, optionally textured to facilitate gripping, and adistal, hooked end 406. The interior surface 408 of hooked end 406comprises a heater wire 410, which is operatively connected through wire412 to a power source (not shown). The distal end 414 of heater wire 410can be spot welded to hooked end 406, which provides a return path forelectricity to the heater wire. Insulative material 416 between heaterwire 410 and hooked end 406 thermally and electrically insulates heaterwire 410. Optionally, insulation material 416 comprises a polymericmaterial in the form of a sleeve.

Elongated member 402 preferably comprises a physiologically acceptable,sterilizable metal such as stainless steel. Non-conductive rigidmaterials can be used so long as a pathway for electricity from thedistal end heater wire 410 is provided.

In FIG. 25 an elongated member 430 has a proximal end 432, optionallytextured, and a distal, hooked end 434. The lateral interior surface 436of hooked end 434 comprises a heater wire 438. Heater wire 438 extendsfrom a spot weld 446 into distal end 434 to a looping point 440 and thenproximally. Through spot weld 446 heater wire 438 is in electricalconnection with elongated member 430. Elongated member 430 is connectedto one pole of a power source (not shown). The other end of heater wire438 extending in the proximal direction after looping point 440 extendsto wire 442 through an electrically and/or thermally shielded pathway444. Wire 442 is connected to the other pole of the power source.

Elongated member 430 comprises a rigid, or substantially rigid,physiologically acceptable, sterilizable material. Useful materialsinclude stainless steel and other conducting metals or alloys. It iswithin the scope of the invention that the distal portion of elongatedmember 430 could be comprised of a rigid or substantially rigidnon-conducting material such as a suitable polymer, for example,polystyrene or an ABS polymer or copolymer

It is intended that all matter contained in the above description andshown in the accompanying drawings shall be interpreted as illustrativeand not in a limiting sense. Also, it is understood that the followingclaims are intended to cover all of the generic and specific features ofthe invention herein described and all statements of the scope of theinvention which, as a matter of language, might be said to falltherebetween.

1. A surgical instrument which comprises two oppositely-positionedworking members each having proximal and distal ends and each having aworking surface, wherein at least one working surface has a heatingelement comprising an electrically resistant wire to seal and cut or cuttissue and the heating element loops around the distal end of a workingsurface and wherein both working surfaces have at least one heatingelement.
 2. A surgical instrument which comprises twooppositely-positioned working members each having proximal and distalends and each having a working surface, wherein each working surface hasa heating element comprising an electrically resistant wire to seal andcut or cut tissue and wherein each heating element loops around thedistal end of a working member.
 3. A surgical instrument which comprisestwo oppositely-positioned working members each having proximal anddistal ends and each having an exterior working surface, wherein atleast one exterior working surface has a distal end and at least oneheating element comprising an electrically resistant wire to seal andcut or cut tissue, wherein a primary switch is actuated when the workingsurfaces are approximated and a secondary switch is manually activatedto apply energy to each heating element.
 4. The instrument of claim 3,wherein the instrument also comprises a battery pack electricallyconnected to each heating element.
 5. The instrument of claim 3, whichalso comprises an elongated member having distal and proximal ends, thedistal end of which is attached to the proximal end of at least oneworking member.
 6. The instrument of claim 3, wherein a working surfacehas more than one heating element.